Chemical delivery system having purge system utilizing multiple purge techniques

ABSTRACT

A chemical delivery system which utilizes multiple techniques to achieve a suitable chemical purge of the chemical delivery system is provided. A purge sequence serves to purge the manifold and canister connection lines of the chemical delivery system prior to removal of an empty chemical supply canister or after a new canister is installed. More particularly, a purge technique which may utilizes a variety of combinations of a medium level vacuum source, a hard vacuum source, and/or a liquid flush system is disclosed. By utilizing a plurality of purge techniques, chemicals such as TaEth, TDEAT, BST, etc. which pose purging difficulties may be efficiently purged from the chemical delivery system. The chemical delivery system may also be provided with an efficient and conveniently located heater system for heating the chemical delivery system cabinet.

This application is a continuation of application Ser. No. 09/325,838filed Jun. 4, 1999, now U.S. Pat. No. 6,199,599, which is acontinuation-in-part of Ser. No. 09/046,907 filed Mar. 24, 1998 U.S.Pat. No. 5,950,693 and a continuation-in-part of Ser. No. 09/105,423filed Jun. 26, 1998, now U.S. Pat. No. 6,029,718 which claims priorityto provisional application Ser. No. 60/052,219 filed Jul. 11, 1997; andthis application claims priority to the following additional U.S.provisional applications Ser. No. 60/088,405 filed Jun. 8, 1998, Ser.No. 60/091,191 filed Jul. 30, 1998, Ser. No. 60/133,936 filed May 13,1999, and Ser. No. 60/134,584 filed May 17, 1999; which is a 371 of PCTapplication number PCT/US98/14373 filed Jul. 10, 1998, which in turnclaims priority to Ser. No. 08/393,913 filed Jul. 11, 1997, andprovisional Ser. No. 60/057,262 filed Aug. 29, 1997; the disclosures allof which are expressly incorporated herein by reference.

BACKGROUND OF INVENTION

This invention generally pertains to systems and manifolds fordelivering chemicals from bulk delivery canisters to manufacturingprocess tools such as chemical vapor deposition (CVD) devices, and moreparticularly for process tools utilized in the fabrication of integratedcircuits.

The production of electronic devices such as integrated circuits is wellknown. In certain steps in such production, chemical may be fed tocertain process tools which use the chemical. For instance, a CVDreactor is commonly employed to generate a layer of a given material,such as a dielectric or conductive layer. Historically, the processchemicals were fed to the CVD reactor via bulk delivery cabinets. Thechemicals used in the fabrication of integrated circuits must have aultrahigh purity to allow satisfactory process yields. As integratedcircuits have decreased in size, there has been a directly proportionalincrease in the need for maintaining the purity of source chemicals.This is because contaminants are more likely to deleteriously affect theelectrical properties of integrated circuits as line spacing andinterlayer dielectric thickness decrease. The increasing chemical puritydemands also impact the chemical delivery systems.

Thus, there exists a need for improved chemical delivery systems suchthat impurities are not introduced into the process tools duringchemical canister replacement or refilling procedures, and othermaintenance procedures. The impurities of concern may include particles,moisture, trace metals, etc. In order to meet these more demandingrequirements, improved manifold systems are required.

Further as chemical purity demands have increased, the variety ofchemicals utilized in integrated circuit manufacturing have increased.Moreover, some of the chemicals being contemplated for integratedcircuit manufacturing exhibit more demanding physical properties and/orare more toxic than previous chemicals utilized, thus placing additionaldemands upon the chemical delivery system. For example, very low vaporpressure chemicals having a vapor pressure of less than 100 mT and evenless than 10 mT are contemplated for use in integrated circuitmanufacturing. One such chemical, TaEth (tantalum pentaethoxide) has avapor pressure of less than 1 mT and is contemplated for use in the CVDformation of dielectric layers. Another such chemical, TDEAT(tetrakis(diethylamido)titanium) has a vapor pressure of approximately 7mT and is contemplated for use in the CVD formation of titanium nitridelayers. Yet another low vapor pressure chemical is TEASate (triethylarsenate). Additional low vapor pressure chemicals may be those utilizedto deposit conductor layers formed of copper or TaN. Because the vaporpressures of such chemicals are so low, traditional methods of purgingthe manifold system of a chemical delivery system are inadequate. Whileexisting manifolds adequately allow traditional compounds to be removedfrom the lines and manifold through repeated vacuum/gas purge cycles,such vacuum/gas purge cycles may not adequately remove very low vaporpressure materials. Thus, a need exists for an improved method andapparatus for purging a manifold system such that very low vaporpressure chemicals may be adequately purged from the various componentsof the chemical delivery system. Further, materials such as TaEth mayrequire heating of the chemical cabinet. It is thus desirable to have achemical delivery system which efficiently incorporates a heating systeminto the gas cabinet.

Other chemicals also place increased demands upon the purging techniquesutilized. For example, chemicals which include solid compounds insolution with a liquid may also be used as reactants in the manufactureof integrated circuits. The solid compounds are typically stored inchemical canisters as dispersions in an organic liquid. For example,solid reactants layers may be dispersed in a liquid such astetrahydrofuran (THF) or triglyme. A wide variety of other solidmaterials may also be used in conjunction with other organic liquids,such as for example as described in U.S. Pat. No. 5,820,664 thedisclosure of which is incorporated herein by reference.

When such solid compositions are sold and used in canisters, thecanisters are often adapted such that they may be connected to amanifold for distribution of the chemical, such as described in U.S.Pat. Nos. 5,465,766; 5,562,132; and 5,607,002. However, when thecanister is changed, existing manifolds do not adequately accommodatethe ability to clean out the manifold and lines prior to change out.Thus, if a vacuum/gas purge cycle is used with a solid/liquidcomposition, the liquid will be evaporated away to leave solid compoundsin the lines. This is unacceptable, especially if the canister is beingchanged out to another compound since the line is contaminated. Particlecontamination and chemical concentration variation may cause severeprocess problems at the process tool. A solution to this problem wouldbe highly desirable.

Further, it is desirable to improve the clean out and purge processesbecause the chemicals utilized may be highly toxic, noxious, etc. Thus,it is desirable to reduce the residual levels of low vapor pressurechemicals (such as discussed herein) within the manifold and lines ofthe chemical delivery system.

Moreover, at least some of the chemicals contemplated for use indeposition systems have ambient temperature requirements which mayrequire elevated temperatures to prevent solidification. Thus, achemical delivery system which addresses the above described problemswhile efficiently and economically providing a controlled temperatureenvironment is desirable.

SUMMARY OF INVENTION

The present invention provides a solution to one or more of thedisadvantages and needs addressed above. More particularly, a chemicaldelivery system which utilizes multiple techniques to achieve a suitablechemical purge of the chemical delivery system is provided. A purgesequence serves to purge the manifold and canister connection lines ofthe chemical delivery system prior to removal of an empty chemicalsupply canister or after a new canister is installed. More particularly,a purge technique which may utilize at least one of a variety ofcombinations of a medium level vacuum source, a hard vacuum source,and/or a liquid flush system is disclosed. By utilizing a plurality ofpurge techniques, chemicals such as TaEth, TDEAT, BST, etc. which posepurging difficulties, may be efficiently purged from the chemicaldelivery system. The chemical delivery system may also be provided withan efficient and conveniently located heater system for heating thechemical delivery system cabinet. Advantageously, the manifold of thisinvention enables improved purge efficiency for low vapor pressurematerials and toxic chemicals.

In one respect, the present invention may include a method of purging alow vapor pressure chemical from a chemical delivery system having aplurality of valves and lines. The method may include utilizing a firstpurging technique to remove chemical, gas, or contaminants from withinat least some of the valves and lines; utilizing a second purgingtechnique to remove chemical, gas, or contaminants from within at leastsome of the valves and lines; and utilizing a third purging technique toremove chemical, gas, or contaminants from within at least some of thevalves and lines. In this method, each of the first, second and thirdpurging techniques may be different. The first purging technique may bea first vacuum step, the second purging technique may be a flowing purgestep utilizing an inert gas, and the third purging technique may be aliquid flush step. Alternatively, the third purging technique may be asecond vacuum step, the first and second vacuum steps utilizingdifferent types of vacuum sources.

Another method according to the present invention is a method ofoperating a chemical delivery system for delivery of chemicals to asemiconductor process tool. The method may include providing at leastone liquid chemical from the chemical delivery system to thesemiconductor process tool; purging at least a portion of the chemicaldelivery system of gas, the liquid chemical or contaminants, the purgingincluding the use of at least three different purging techniques; andchanging at least one canister of the chemical delivery system, thecanister containing the at least one liquid chemical.

In yet another embodiment of the present invention, a method of purginga low vapor pressure liquid chemical from a chemical delivery system isprovided. The method may include providing the low vapor pressure liquidchemical to at least one line or valve of the chemical delivery system;and purging the at least one line or valve of the low vapor pressureliquid chemical, the purging including the use of at least threedifferent purging techniques. The low vapor pressure liquid chemical maybe TaEth, TDEAT or BST or other low vapor pressure chemicals.

In another embodiment, a method of forming a dielectric layer upon asemiconductor substrate is provided. The method includes providing thesemiconductor substrate, the substrate having one or more layers;providing a deposition process tool; and coupling a chemical deliverysystem to the deposition process tool to provide a low vapor pressureliquid chemical to the deposition process tool. The method furtherincludes periodically purging at least a portion of the chemicaldelivery system of the low vapor pressure liquid chemical, the purgingincluding the use of at least three different purging techniques; anddepositing the dielectric layer upon the semiconductor substrate byutilizing the low vapor pressure liquid chemical within the depositionprocess tool. The low vapor pressure liquid chemical may be TaEth orBST.

In still another embodiment, a method of forming a layer containingtitanium upon a semiconductor substrate is provided. The method mayinclude providing the semiconductor substrate, the substrate having oneor more layers; providing a deposition process tool; and coupling achemical delivery system to the deposition process tool to provide a lowvapor pressure liquid chemical to the deposition process tool. Themethod may also include periodically purging at least a portion of thechemical delivery system of the low vapor pressure liquid chemical, thepurging including the use of at least three different purgingtechniques; and depositing the layer containing titanium upon thesemiconductor substrate by utilizing the low vapor pressure liquidchemical within the deposition process tool. The low vapor pressureliquid chemical may be TDEAT. The layer may comprise titanium nitride.

In one embodiment, the present invention may be a chemical deliverysystem. The chemical delivery system may include at least one canisterinlet and at least one canister outlet line; a plurality of manifoldvalves and lines; a first purge source inlet coupling a first purgesource to the plurality of manifold valves and lines; a second purgesource inlet coupling a second purge source to the plurality of manifoldvalves and lines; and a third purge source inlet coupling a third purgesource to the plurality of manifold valves and lines, the first, secondand third purge sources each being different types of purge sources. Thefirst purge source may be a first vacuum source, the second purge sourcemay be a gas source and the third purge source may be a liquid source.Alternatively, the third purge source may be a second vacuum source, thefirst and second vacuum sources being different types of vacuum sources.

In another embodiment, a chemical delivery system for delivery of lowvapor pressure liquid chemicals to a semiconductor process tool isprovided. The system may include at least one chemical output line, thechemical output line coupled to the manifold of the chemical deliverysystem and operable to provide the low vapor pressure liquid chemical tothe semiconductor process tool; at least three purge source inlet lines,the purge source inlet lines coupling at least three different purgesources to the manifold; and one or more refillable canisters coupled tothe manifold. The one or more refillable canisters may comprise at leasta first canister and a second canister. Further the low vapor pressureliquid chemical may be provided to the semiconductor process tool fromthe second canister, the chemical delivery system being capable ofrefilling the second canister from the first canister. The system mayalternatively be capable of providing liquid chemical from both thefirst canister and the second canister to the semiconductor processtool.

Another embodiment of the invention disclosed herein may include acabinet for housing a chemical delivery system. The cabinet may includea plurality of cabinet walls forming an interior cabinet space, at leastone of the cabinet walls being a door; at least one heater elementdisposed in or adjacent to the door; and an air flow passage in closeproximity to the at least one heater element. The cabinet may furtherinclude at least one heat exchange element within the air flow passage,the heat exchange element being thermally coupled to the heater. Theheat exchange element may be a plurality of fins. The air flow passagemay be formed along a back side of a wall of the door and the heaterelement may be formed along a front side of the wall of the door. Thedoor of the cabinet may have a cavity and an interface structure withinthe cavity, the interface structure forming at least a portion of thewall of the door. The heater may be recessed within the door.

Another embodiment of disclosed invention may include a temperaturecontrolled cabinet for housing a liquid chemical delivery system. Thecabinet may include at least one door; at least one heater elementdisposed in or on the door; an air vent within the door; and an air flowpassage in close proximity to the at least one heater element, the airflow passage thermally communicating with the at least one heaterelement, the air vent providing an air inlet for the air flow passage.

In still another embodiment, a temperature controlled cabinet forhousing a liquid chemical delivery system is provided. The cabinet mayinclude a plurality of cabinet walls; and at least one heater elementdisposed in or on at least a first cabinet wall, the heater elementbeing located on exterior side of the first cabinet wall and thermalenergy from the heater being coupled to the interior of the cabinetthrough the first cabinet wall. The first cabinet wall may be at least aportion of a cabinet door. The cabinet may further comprise an airpassage adjacent an interior side of the first cabinet wall.

Yet another embodiment of the present invention is a method ofcontrolling the temperature of a cabinet housing a chemical deliverysystem. The method may include providing a plurality of cabinet wallsforming an interior cabinet space; locating at least one heater elementwithin or in close proximity to at least a first cabinet wall; andthermally transferring energy from the heater to the interior cabinetspace utilizing the first cabinet wall as a heat transfer mechanism.

In yet another embodiment, a method of controlling the temperature of acabinet housing a liquid chemical delivery system is provided. Themethod may include providing a plurality of cabinet walls forming aninterior cabinet space; locating at least one heater element on anexterior side of at least a portion of a first cabinet wall; thermallytransferring energy from the heater to an interior side of the firstcabinet wall, utilizing the first cabinet wall as a heat transfermechanism; and heating the interior cabinet space by flowing air acrossthe interior side of the first cabinet and circulating side air withinthe interior cabinet space.

Still another embodiment of the present invention is a chemical deliverysystem manifold useful for delivery of liquid chemicals from a canister.The manifold may include a vacuum supply valve coupled to a vacuumgenerator; a pressure vent valve coupled to the vacuum generator; and acarrier gas isolation valve coupled to a carrier gas source. Themanifold further includes a process line isolation valve coupled to abypass valve and a canister outlet line, the canister outlet linecapable of being coupled to a canister outlet valve; a flush inlet valvecoupled between the carrier gas isolation valve and the bypass valve,the flush inlet valve capable of being connected to a liquid flushsource; and a canister inlet line capable of being coupled between acanister inlet valve and the bypass valve.

Also disclosed is a chemical delivery system manifold useful fordelivery of liquid chemicals from a canister. The system may include afirst vacuum supply valve for coupling the manifold to a first vacuumsource; a second vacuum supply valve for coupling the manifold to asecond vacuum source, the first and second vacuum sources beingdifferent types of vacuum sources; and a pressure vent valve coupled toeither or both of the first and second vacuum sources. The system mayalso include a carrier gas isolation valve coupled to a carrier gassource; a process line isolation valve coupled to a bypass valve and acanister outlet line, the canister outlet line capable of being coupledto a canister outlet valve; and a canister inlet line capable of beingcoupled between a canister inlet valve and the bypass valve. Themanifold may also include a flush inlet valve coupled between thecarrier gas isolation valve and the bypass valve, the flush inlet valvecapable of being connected to a liquid flush source.

In another embodiment a chemical delivery system is disclosed. Thechemical delivery system may include (1) a vacuum supply valve; (2) avacuum generator; (3) a carrier gas isolation valve; (4) a bypass valve;(5) a process line isolation valve; (6) a liquid flush inlet valve; (7)a low pressure vent valve; (8) a canister inlet valve; and (9) acanister outlet valve. The system may be configured such that the vacuumsupply valve is connected to the vacuum generator; the carrier gasisolation valve is connected to the liquid flush inlet valve; and theliquid flush inlet valve is connected to the bypass valve. Also, thebypass valve is further connected to the process line isolation valve;the low pressure vent valve is connected to the vacuum generator; theprocess line isolation valve is also connected to the canister outletvalve; and the canister inlet valve is connected to the canister outletvalve.

Also disclosed is a method of purging a low vapor pressure liquidchemical from a chemical delivery system. The method may includeproviding a manifold. The manifold may comprise a vacuum supply valvecoupled to a vacuum source, a pressure vent valve coupled to the vacuumsupply valve, a carrier gas isolation valve coupled to a carrier gassource, a process line isolation valve coupled to a bypass valve and acanister outlet line, the canister outlet line capable of being coupledto a canister outlet valve, a flush inlet valve coupled between thecarrier gas isolation valve and the bypass valve, the flush inlet valvecapable of being connected to a liquid flush source, and a canisterinlet line capable of being coupled between a canister inlet valve andthe bypass valve. The method also comprises providing the low vaporpressure liquid chemical to at least one line or valve of the chemicaldelivery system; and purging the at least one line or valve of the lowvapor pressure liquid chemical, the purging including the use of atleast three different purging techniques.

In still another embodiment, a method of purging a low vapor pressureliquid chemical from a chemical delivery system is provided. The methodmay include providing a manifold. The manifold may comprise a vacuumsupply valve coupled to a vacuum source, a pressure vent valve coupledto the vacuum supply valve, a carrier gas isolation valve coupled to acarrier gas source, a process line isolation valve coupled to a bypassvalve and a canister outlet line, the canister outlet line capable ofbeing coupled to a canister outlet valve, and a canister inlet linecapable of being coupled between a canister inlet valve and the bypassvalve. The method may further comprise providing the low vapor pressureliquid chemical to at least one line or valve of the chemical deliverysystem; purging the at least one line or valve of the low vapor pressureliquid chemical, the purging including the use of at least threedifferent purging techniques.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B depict a representative chemical delivery system of thepresent invention.

FIGS. 2A, 2B, and 2C illustrates alternative purge configurationsaccording to the present invention.

FIGS. 3A, 3B, and 3C illustrate alternative purge configurationsaccording to the present invention.

FIGS. 4A-4R illustrate manifold systems utilizing a medium level vacuum,a flowing purge and a liquid flush.

FIGS. 5A-5M illustrate a dual tank chemical delivery system having amedium level vacuum, flowing purge and flush liquid purge.

FIGS. 6A-6N illustrate a dual tank refillable chemical delivery systemhaving a medium level vacuum, flowing purge, and hard vacuum.

FIGS. 7A-7M illustrate a dual tank chemical delivery system having amedium level vacuum, flowing purge, flush liquid purge and hard vacuum.

FIG. 8 illustrates a cabinet for a chemical delivery system.

FIGS. 9A and 9B illustrate a door for use with a chemical deliverysystem cabinet.

DETAILED DESCRIPTION OF THE INVENTION

The problems discussed above and others are addressed through the use ofa chemical delivery system which utilizes multiple techniques to achievea suitable chemical purge of the chemical delivery system. A purgesequence serves to purge the manifold and canister connection lines ofthe chemical delivery system prior to removal of an empty chemicalsupply canister or after a new canister is installed.

The types of chemicals which may be utilized with the present inventionmay vary widely depending on the type of process tool and desiredoutcome. The techniques of the present invention are particularlyadvantageous for use with liquid chemical delivery systems in whichliquids are supplied for use with CVD systems, such as for example, asused in semiconductor manufacturing. Non-limiting examples ofrepresentative chemicals include TDEAT, tetraethylorthosilicate(“TEOS”), triethylphosphate, trimethyl phosphite, trimethyl borate,titanium tetrachloride, tantalum compounds such as TaEth, and the like;solvents such as chlorinated hydrocarbons, ketones such as acetone andmethylethylketone, esters such as ethyl acetate, hydrocarbons, glycols,ethers, hexamethyldisilazane (“HMDS”), and the like; solid compoundsdispersed in a liquid such as barium/strontium/titanate cocktails(mixtures). These examples of chemicals are not intended to be limitingin any way. The chemicals may be of a variety of purities, and mixturesof chemicals can be used. In one embodiment, a single type of chemicalis employed. A given chemical may advantageously have a purity of99.999% or more with respect to trace metals. In one embodiment of thisinvention, the canister 104 is at least partially filled with a chemicalwhich is at least 99.99999999% pure based on the amount of trace metalsin the chemical. The chemicals and delivery systems disclosed herein maybe used in conjunction with any of a wide variety of process tools suchas LPCVD, PECVD, APCVD, MOCVD, etc. tools.

More particularly, according to the present invention a purge techniquewhich utilizes a variety of combinations of some or all of the followingpurge techniques: a first vacuum source, a flowing purge (i.e. a flow ofan inert gas to flush process chemical out of the manifold lines), asecond vacuum source, and/or a liquid flush system. The first and secondvacuum sources may generally be different vacuum sources that may havedifferent vacuum levels. In one example, the first vacuum sources may bea vacuum typically in the range of less than 100 T, and more typically50 to 100 T, and such vacuum sources may be called “medium levelvacuums”. Further in such example, the second vacuum source may be avacuum typically less than 100 mT and more typically in the range of 100mT to 1 mT, and such vacuum sources may be called a hard vacuum.However, it will be recognized that the levels disclosed herein areillustrative and other higher or lower vacuum levels may be utilized forthe first and second vacuum sources. In one embodiment the first (ormedium level) vacuum source may be a Venturi vacuum source. By utilizinga plurality of purge techniques, chemicals such as TaEth, TDEAT, BST,etc. which pose purging difficulties may be efficiently purged from thechemical delivery system.

FIG. 1A represents a chemical delivery system 100 configured to utilizemultiple purge techniques. The chemical delivery system 100 shown inFIG. 1A is a single tank chemical delivery system for illustrativepurposes to demonstrate the principles of the present invention. Thesystem may be any of a number of differently configured systems such asa dual tank non-refillable system (two chemical canisters without theability to refill one canister with the other), a dual tank refillablesystem (two chemical canisters with the ability to refill one canisterwith the other), a bulk delivery system utilizing a large bulk canisterto refill one of more process canisters (within or remote from thechemical delivery system), a system having three canisters or more, etc.For illustrative purposes, FIG. 1B represents a chemical delivery system100 utilizing two chemical canisters.

As shown in FIGS. 1A and 1B, the chemical delivery system 100 includes amanifold system 102. The manifold system includes the valves and linesof the chemical delivery system. Though shown as a single block, themanifold system may be comprised a plurality of manifold systems (orsub-manifolds). Thus, it will be recognized that the term manifold mayrefer to all the valves and lines of the delivery system and also may beused to refer to some portion of the valves and lines. The manifold(s)may be formed in a single chemical delivery system cabinet or may bedistributed amongst a plurality of cabinets or even located outside of acabinet. The system 100 may also include a canister 104 (or canisters104A and 104B as shown in FIG. 1B), and a chemical outlet line 110 (alsoreferred to as a process line) to provide chemical to a process toolsuch as a chemical vapor deposition tool. Though shown as one outletline 110, line 110 may be comprised of two or more branch lines andassociated branch isolation and purge lines. The system 100 alsoincludes canister inlets and outlets 108 and 106 respectively (or inlets108A and 108B and outlets 106A and 106B as shown in FIG. 1B). Coupled tothe manifold system 102 are four input lines utilized for purgingactivities, a medium level vacuum line 112, a purge gas input 111, ahard vacuum line 114, and a liquid flush line 116. A waste output line118 is also provided. The waste output may be coupled to a waste outputcontainer (within or remote to the delivery system) or a dedicated wasteline in a user's facility. The medium level vacuum line 112 may becoupled to a medium level vacuum source such as a Venturi vacuumgenerator. The purge gas input 111 may be connected to an inert gas linesuch as a helium, nitrogen or argon line in order to create a flowingpurge through the manifold. The hard vacuum line 114 may be connected toa hard vacuum source such as a stand alone vacuum pump. However, in apreferred embodiment the hard vacuum source may be the process toolvacuum as described in more detail below. The liquid flush line 116 maybe a source for a flush liquid such as solvents tetrahydrofuran (THF) ortriglyme. The particular solvent used will vary depending onavailability, cost and the type of materials being purged from thelines. In general, the solvent will be matched to allow for adequatedispersion of solid chemicals, solubization of thick materials, dilutionof high vapor pressure chemicals (without solidification of thechemicals due to presence of the solvent), and the like. For example, ifa solid active chemical dispersed in triglyme is being purged, triglymemay be used to initially clean out the lines optionally followed bytreatment with THF to remove trace amounts of triglyme. Alternatively,THF may alone be used, circumstances permitting. In another example,TaEth is flushed with ethanol or hexene. Other examples may includeusing n-butyl acetate to flush BST contained in a butyl acetatesolution. The liquid flush line 116 may be coupled to a dedicated flushliquid canister or alternatively may be coupled to the liquid supplylines in a user's facility. The medium level vacuum line 112, purge gasline 111, hard vacuum line 114 and liquid flush line 116 may each beused to help purge from the manifold system 102 hard to purge chemicalssuch as TaEth, TDEAT, BST, etc. The present invention may also beutilized while using less than all four of the input lines. Thus asshown as exemplary embodiments in FIGS. 2A, 2B, and 2C, a combination ofless than four of the input lines may be used.

By utilizing a plurality of purging techniques in combination (mediumlevel vacuum, flowing purge, hard vacuum, or liquid flush) theparticular benefit of each technique may be advantageously utilizedwhile any disadvantages of a particular technique are minimized. A hardvacuum is advantageous in that lower pressures may be obtained. However,a stand alone hard vacuum source generally is more expensive, requiresmore maintenance, is larger, requires more facilities, and creates morewaste as compared to Venturi vacuum sources. By utilizing a Venturimedium level vacuum system, though, a stand alone hard vacuum source isnot necessary. Rather, the hard vacuum source typically present in aprocess tool may be tapped into. The process tool hard vacuum source maybe utilized by itself or subsequent to use of the Venturi vacuum tolower pressures within the manifold system 102. Then the hard vacuumfrom the process tool may be switched on to lower the pressure levelswithin the manifold even further. By first utilizing the medium levelvacuum to lower pressures, the hard vacuum is placed under less load. Bylowering the load on the hard vacuum, the hard vacuum source internal tothe process tool may be utilized without jeopardizing the quality of anyprocess being performed within the process tool. Thus, the use of theVenturi vacuum allows the use of a readily available hard vacuum sourcewithout the additional costs associated with stand alone hard vacuumsources or dedicated hard vacuum sources.

Similarly, flushing a manifold with a liquid in combination with one ormore vacuum sources is an advantageous purge technique. If the chemicalbeing delivered is solid suspended in an organic liquid, the manifoldmay be designed so as to allow for liquid flush of all the lines toprevent solids accumulating in the lines upon evaporation of the organicliquid. If dispersions are employed, it is preferable to flush the linesout with liquid solvents such as triglyme or tetrahydrofuran (THF) sothat compounds are not precipitated in the lines when the lines aredepressurized. For example, a liquid flush may be utilized prior to avacuum purge in order to remove any solid residues which may result whenvacuum pumping a manifold which contains certain solid containingchemicals such as BST. In addition, a liquid flush may provideadvantages to help remove very low vapor pressure chemicals from pipingthat has long lengths and/or is narrow (situations in which even a hardvacuum may not adequately purge a manifold).

When a liquid flush is utilized, a variety of methods for injecting andremoving the liquid from the manifold may be utilized. FIGS. 3A, 3B, and3C illustrate three examples for injecting and removing the liquid fromthe manifold; however, other techniques may also be used. Further,though for illustrative purposes, FIGS. 3A, 3B, and 3C show purgetechniques in combination with a dual tank system having both a mediumlevel vacuum input 112, a purge gas input 111 and a hard vacuum input114. The purge techniques shown may be utilized with the othersystem/canister configurations discussed herein. As shown in FIG. 3A, aflush liquid input 116 may be provided. In one configuration the flushliquid may be supplied from a dedicated chemical supply line 121 of auser's standard facilities lines. The liquid waste generated by theliquid flush activities may be provided to a waste container 120. Analternate configuration of the system of FIG. 3A may be a system withoutthe flush liquid input 116 and the waste container 120. Such a systemwould thus utilize three purging techniques, a medium level vacuumpurge, a hard vacuum purge, and a flowing gas purge. As shown in FIG.3B, a combination flush liquid source and waste container 122 may beutilized. In this configuration, liquid to flush the manifold 102 issupplied from the container 122 and also returned to the container 122as waste through lines 123A and 123B. FIG. 3C illustrates yet anotherconfiguration in which a dedicated liquid source container 124 suppliesflush liquid through the use of lines 125A and 125B and a dedicatedliquid waste container collects the liquid waste through lines 118A and118B. As will be described in more detail below, the waste containersneed not only collect flush liquids but may also collect process liquidswhich are drained from at least some of the manifold lines as part ofthe purging process. It will be recognized that canisters 124, 122 and120 (or other portions of chemical delivery system) may be locatedintegrally within one chemical delivery system housing or may be locatedexternal to the chemical delivery system and that functionally, thesystems disclosed herein would operate the same independent of theplacement of the canisters.

For some embodiments of the inventions disclosed herein, the preciseconfiguration of the manifold 102 is not critical in the practice ofthis invention so long as the function of providing a stream of chemicalto the process tool and allowing an adequate purge is achieved. Theconfiguration of the valves in the manifold 102 may be varied to allowfor independent purging and maintenance of individual lines.

It will be recognized that many manifold and canister configurations mayalso be utilized according to the present invention, including but notlimited to the illustrative examples discussed in more detail below.Additional manifold configurations such as described in U.S. Pat. Nos.5,465,766; 5,562,132; 5,590,695; 5,607,002; and 5,711,354, all of whichare incorporated herein by reference, may also be utilized withappropriate modifications to accommodate a flowing purge, a liquid flushand/or a hard vacuum.

A manifold for use with the present invention may be advantageouslydesigned such that there are no un-purged dead legs in the manifold,lines, and fittings. In this regard, the design may advantageouslyminimize bends in tubing interconnection lines and flex lines byutilizing short straight lines when possible. Further, the design mayadvantageously utilize SVCR fittings (straight VCR fittings). Ingeneral, pressure in the system is adjusted so that pressure on theupstream side is higher than on the downstream side. It should beappreciated that a wide variety of valves may be used in the manifold,including but not limited to manually activated valves, pneumaticallyactivated valves, or any other type of valve. The manifold valves may becontrolled using process control instrumentation. The controller mayadministrate a purge sequence and a normal run mode. During a ran mode,the system will provide chemical to the process tool, which may beinitiated after installation of a bulk chemical supply.

Typically, the entire manifold system may be cleared or purged ofprocess chemical prior to a canister change-out or shut down byalternating flowing gas purges, vacuum cycles and/or liquid purges. Abrief overview of typical cycling is first provided herein with moredetailed examples following. Generally to begin a purge cycle thechemical canister is first pressurized. Then a vacuum line dry down maybe accomplished through the use of a cycle purge. As used herein a cyclepurge is vacuum step flowed by a flowing gas purge. The cycle purge maybe repeated any number of times to obtain the desired dry down orremoval of chemical. The vacuum line dry down step removes moisture fromthe vacuum lines from reacting with chemicals in the lines between thecanister outlet and the process line output 110. The vacuum could be amedium level vacuum generated from a Venturi generator and/or a hardvacuum from a vacuum pump. After the line dry down, the manifold lineswhich are exposed to and contain the process chemical are drained backinto the canister (into the canister output).

After the line drain, the general purge sequences may vary dependingupon whether a liquid flush or a hard vacuum is utilized. For example,if a liquid flush is utilized (without a hard vacuum), the manifoldlines which were exposed to the process chemical are flushed with theliquid solvent. Then, these lines are subject to cycle purge of a mediumlevel vacuum followed by a flowing purge of an inert gas in order toremove any residual solvent vapors. The canister may then be removed orexchanged. During the canister change, the flowing purge may continue inorder to prevent ambient atmosphere from entering and contaminating themanifold. After a new canister is attached to the manifold a final cyclepurge of vacuum step followed by a flowing gas purge may be performed toremove any traces of atmosphere from the fittings of the new canister.

If a hard vacuum is utilized with a liquid flush, the general purgesequence after a line drain may be as follows. After the line drain, themanifold lines which were exposed to the process chemical are subjectedto a medium level vacuum. Next: these lines are subjected to the hardvacuum. The medium level vacuum is utilized first so as to minimize theload upon the hard vacuum as discussed above. Then a flowing purge maybe initiated prior to and during the canister change. After the canisterchange, a cycle purge may be initiated followed by a hard vacuum finalpumpdown.

A non-limiting example of a representative manifold design isillustrated in FIGS. 4A-4I. FIGS. 4A-4I illustrate one embodiment of amanifold system having multiple purging techniques. For illustrativepurposes, FIGS. 4A-4I illustrate the use of a medium level vacuum,flowing purge and liquid flush as the plurality of purging techniques.Moreover, a single canister system is also shown for demonstrativepurposes and the inventions disclosed herein are not limited to thesespecific examples. For each of the valves in the figures, the opentriangles represent lines which are always open, with the darkenedtriangles being closed until opened.

In FIG. 4A, a vacuum source 14 such as a Venturi vacuum generator may beconnected to vacuum supply valve (“VGS”) 10 via line 12. VGS 10functions to control the flow of gas (such as nitrogen, helium, orargon) via inert gas line 11 to the vacuum source 14 if the vacuumsource is a Venturi vacuum generator. Vacuum source 14 may also beattached to exhaust line 13 which exits to exhaust. Vacuum source 14 maybe connected to low pressure vent valve (“LPV”) 60. In FIG. 4A, vacuumsource 14 is connected to LPV 60 via line 15 and line 16. Check valve33A in line 37 is closed unless and until the manifold eclipses thedesired release pressure. Line 37 is vented to the cabinet exhaust.Generally, the check valve 33A may be set to activate if the manifoldpressure surpasses a preset level, such as about 75 pounds per squareinch. The check valve is coupled to the carrier gas isolation valve(“CGI”) 30. CGI 30 may also be referred to as a carrier gas inlet valve.The check valve serves to vent gas if pressure in the system reaches aselected level. Line 31 may connect CGI 30 to regulator 32 which maysupply a flow of pressurized inert gas. A delivery pressure gauge 36 maybe tied into regulator 32 to monitor regulator pressure and pressureduring all operations.

In FIG. 4A, flush line inlet valve (“FLI”) 45 may be coupled to CGI 30through line 33. FLI 45 is coupled to the flush liquid input 116. Line34 may connect FLI 45 to canister bypass valve (“CBV”) 40. Lines 41 and42 may attach CBV 40 to process line isolation valve (“PLI”) 50 and tocontrol valve (“CP2”) 70 respectively. PLI 50 is coupled to the processline output 110. The function of PLI 50 is to control the flow ofchemical out of the manifold. CGI 30 functions to control thepressurized gas supply to the manifold. The function of CBV 40 is tocontrol the supply of pressure or vacuum to PLI 50 and to line 71. Line110 may carry chemicals to either a process tool outside the deliverysystem, or in a dual tank refill system, to another canister to berefilled. A canister outlet line 52 may serve to link PLI 50 to canisteroutlet valve (“CO”) 92. Line 62 may connect CP2 70 to Liquid WasteOutput valve (“LWO”) 61. LWO 61 is connected to the waste output line118. LWO 61 is also coupled to LPV 60 through line 63. From controlvalve 70, the canister inlet line 71 may lead to canister inlet valve(“CI”) 90. CI 90 functions to control pressurization and evacuation of acanister. Line 73 may link CO 92 and CI 90. CO 92 functions to controlthe flow of chemical from a canister 110 during chemical delivery andthe purging of the canister outlet weldment during canister changes. CI90 and CO 92 serve to couple the manifold to the correspondingstructures on a chemical canister 104, typically in conjunction withfittings such as male and female threaded joints. Fittings (couplers) tojoin the manifold to canister 104 are typically present in lines 71 and52. CO 92 is a dual activator valve such that line 73 connects the dualactivator valve directly to CI 90. Alternatively if CO 92 is not a dualactivator valve, an additional valve may be placed above CO 92 and anadditional line placed from the additional valve to couple theadditional valve to line 71.

The aforementioned lines, which may also be referred to as conduits,tubing, pipes, passages, and the like, may be constructed of many typesof materials, for example, such as 316L stainless steel tubing, teflontubing, steel alloys such as Hastalloy, etc. Each of the valves may beconventional pneumatically actuated valves, such as a NUPRO6L-M2D-111-P-III gas control valve. Likewise, the regulator can be astandard type, such as an AP Tech 1806S 3PW F4-F4 V3 regulator. Thesystem may be assembled using conventional methods, such as by usingpressure fitting valves, by welding, and the like. The valves may becontrolled using conventional process control such as an Omronprogrammable controller box wired to a touch screen control panel.Alternatively, the valves may be controlled using an ADCS APC™Controller which incorporates an imbedded microprocessor for commandsequence execution, with software residing on an EPROM. The controlunit, for example, may control flow of pressurized gas to open or closepneumatic valves.

During use, the manifold of this invention may be operated as follows.To push chemical out of the canister 104 to the delivery point, thevalves in the manifold are appropriately opened and closed to allowpressurized gas into the system and into the canister. In FIG. 4B,dashed line 220 illustrates the path of pressurized gas enteringcanister 104, with dashed line 221 showing the path of liquid chemicalexiting canister 104 through a dip tube 91. Thus, pressurized gas from asource (not shown) is released by regulator 32 into line 31. The gasthereafter passes through open CGI 30, then through line 33, FLI 45, CBV40, line 42, opened CP2 70, line 71, CI 90, and into canister 104.Pressure from entering gas forces liquid chemical up the dip tube, andthrough CO 92, line 52, PLI 50, and out line 110 to the receiving point(for example, a CVD process tool).

When a supply canister (even a full canister) is being changed out, thelines may be purged to rid the manifold of residual chemicals. The firststep to rid the manifold of residual chemicals is a cycle purge stepwhich includes a vacuum step and a flowing puree step respectively. Thecycle purge may include repeatedly performing the vacuum and flowingpurge in an alternating manner. A single vacuum step is discussed belowwith reference to FIG. 4C and a single flowing purge step is discussedbelow with reference to FIG. 4D. The vacuum step may be accomplished ina variety of ways, including via the configuration depicted by dashedline 250 FIG. 4C. Thus, in one embodiment, LPV 60 and CP2 70 are openedsuch that when VGS 10 is opened to allow gas into vacuum source 14 vialines 11 and 12, a vacuum is drawn out to exhaust via line 13, with avacuum thus being pulled on lines 15, 16,63,62,42,34,33,71, and 73.

In FIG. 4D, a flowing purge of the vacuum line dry down cycle purge isillustrated. In FIG. 4D, regulator 32 allows pressurized gas to enterline 3 1. With CGI 30, CP2 70, and LPV 60 open, the gas flows throughlines 31, 33, 34, 42, 71, 73, 62, 63, 16, 15, and 13 to thereby purgethe manifold, as depicted in FIG. 4D by dashed line 260. One advantageof this step is to remove moisture and oxygen from lines such as lines13, 15 and 16.

Next a depressurization step is performed to remove the head pressure incanister 104. For example, a procedure by which depressurization mayoccur is depicted in FIG. 4E. In one depressurization method, depictedby dashed line 230, VGS 10 is opened to allow gas to flow from line 11through line 12 and into vacuum source 14 such that a vacuum isgenerated with the flow exiting via line 13 to exhaust. The vacuum whichis generated in source 14 pulls a vacuum on line 15, line 16, throughopen LPV 60, line 63, through LWO 61, line 62, CP2 70, line 71, and openCI 90, thereby pulling a vacuum on the head space of canister 104.

After depressurization, a liquid drain is instituted to clear the lines(weldments) of liquid. Thus, in FIG. 4F gas is introduced via regulator32 into line 31. CGI 30, CBV 40, and CO 92 are open such that gas flowsthrough lines 31, 33, 34, 41, and 52 such that liquid chemical is forcedback into canister 104. The flow of gas during the line drain isillustrated by dashed line 240. The depressurization followed by aliquid drain sequence shown in FIGS. 4E and 4F may be repeatedlyperformed to remove all liquid from the valves, tubes, and fittings.

After the liquid drain, a flush liquid purge is instituted. As shown inFIG. 4G, a flush liquid may be introduced though flush liquid input 116.By opening FLI 45, CBV 40, and part of CO 92, flush liquid purges allwetted surface areas on the outlet of the manifold. Thus, flush liquidflows through lines 34, 41, 52, 73, 71, and 62 as shown by dashed line270. Further, LWO 61 is opened so that the flush liquid may exit themanifold 102 through the waste outlet 118. Multiple cycles of a linedrain of the flush lines may then be executed by using the sameconfiguration as shown in FIG. 4G except closing FLI 45 and opening CGI30 to flow purge gas through the lines 34, 41, 52, 73, 71, and 62 andrepeating the cycle.

After the liquid purge and line drain of the flush lines, a canisterremoval cycle purge is instituted which includes a vacuum step and aflowing purge step respectively. This cycle purge removes any residualsolvent vapors remaining after the flush liquid purge step. The vacuumstep is depicted by dashed line 280 in FIG. 4H. Thus, in one embodiment,LPV 60, part of CO 92, and CBV 40 are opened such that when VGS 10 isopened to allow gas into vacuum source 14 via lines 11 and 12, a vacuumis drawn out to exhaust via line 13, with a vacuum thus being pulled onlines 15, 16, 63, 62, 71, 73, 52, 41, 34, and 33.

In FIG. 4I, a flowing purge is instituted as part of the canisterremoval cycle purge. In FIG. 4I, regulator 32 allows pressurized gas toenter line 31. With CGI 30, CBV 40, part of CO 92, and LPV 60 open, thegas flows through lines 31, 33, 34, 41, 52, 73, 71, 62, 63, 16, 15, and13 to thereby purge the manifold, as depicted in FIG. 4I by dashed line290.

After purge, the fittings are typically broken while a positive pressureon the manifold is maintained so that moisture does not enter themanifold. For instance, CGI 30, CBV 40, CO 92, CI 90 and CP2 70 may beopened so that gas flows out lines 52 and 71 after the fittings arebroken. After a new canister is seated, the canister removal cycle purgeas shown in FIGS. 4H and 4I is typically repeated to remove any water,traces of atmosphere or other contaminant that might have entered themanifold, as well as any water, atmosphere, or contaminants in thefittings and weldments of the new canister.

The embodiment of the invention discussed with reference to FIGS. 4A-4Ihas many advantages compared to standard manifolds including a reducednumber of valves which results in lower cost of the manifold, areduction in the number of points where a leak may occur as well as areduction in the chances for valve failure for a given manifold. Thisembodiment also reduces the number of dead legs in the system, resultingin a more effective flowing purge. Owing to the improved ability toremove chemicals from the lines during canister changes, the manifold ofthis embodiment provides a system which may be used with hazardouschemicals, such as arsenic compounds. Likewise, this manifold embodimentpermits improved use of dispersions, such as metals or solid compoundsdispersed in an organic carrier liquid such as diglyme and triglyme. Ifdispersions are employed, it is preferable to flush the lines out withliquid solvents such as triglyme or tetrahydrofuran (THF) so thatcompounds are not precipitated in the lines when the lines aredepressurized. Additionally, for any of the embodiments of thisinvention, it is contemplated that the manifold can be heated toaccelerate evaporation of chemicals in the lines. In this regard, themanifold can be maintained in a heated environment, wrapped with heatingtape connected to a variac or the like. Alternatively, a heating elementmay be configured with the cabinet door as shown below with reference toFIGS. 10A and 10B. To facilitate evaporation during a flowing purge,heated gas could alternatively be employed, such as heated argon,nitrogen, or other inert gas. Combinations of these techniques can alsobe employed. For some types of chemicals, it may be possible to purgewith reactive chemicals, which react with one or more of the compoundsin the line to produce more readily evacuated compounds.

The manifolds of this invention may include a sensor attached, forexample, in line 15 to determine whether the lines of the manifoldcontain any chemical. Similarly, a sample port could be included in line15 where a sample of gas from the line can be withdrawn and tested usingan analytical device to test for the presence of chemical.

An alternative embodiment of the present invention, similar to theembodiment of FIGS. 4A-4I, is shown in FIG. 4J. The embodiment of FIG.4J is the same as the embodiment of FIG. 4A except that CP2 70 of FIG.4A has been removed. More particularly, as shown in FIG. 4J, CP2 is notutilized to join lines 62, 71 and 42 but rather a T fitting 44 and acritical orifice 43 are utilized to join lines 62, 71, and 42. Thecritical orifice 43 operates as a flow restriction device to limit(though not prevent) gas flow from line 42 to T fitting 44. The criticalorifice 43 may be constructed in a wide range of manners. For example,the orifice 43 may be formed to have a region of narrowing innerdiameter as compared to the inner diameter of the other piping, such asline 42 and/or T fitting 44. The narrowing region will thus tend todivert gas flow. For example, if CBV 40 is opened then gas flowing fromline 34 to CBV 40 will preferentially flow at higher volumes out CBV 40through line 41 as compared to the flow through line 42 and the orifice43 due to the restriction effect of the orifice 43. As will be shownbelow, the use of the orifice 43 allows for the generation of gas flowpatterns similar to those shown in FIGS. 4B-4I while utilizing one lessvalve.

In one embodiment, the orifice 43 may be formed by use of a VCR fittingwhich joins line 42 and T fitting 44. The VCR fitting may have a gasketwithin the fitting which has a narrower opening as compared to the innerdiameter of the line 42 and the T fitting 44. For example, the orificemay have an opening diameter of {fraction (1/32)} inch or {fraction(1/16)} inch while the line 42 may be constructed of ¼ inch pipinghaving an inner diameter of 0.18 inch. The ratio of such diameters willresult in a flow restriction through the orifice as compared to othersegments of the manifold system. As will be shown below, the gas flowthrough the orifice will be utilized during steps where a canister isbeing pressurized, such is for example when chemical is being pushed outof the canister to the chemical delivery point. Thus, the suitable sizeof the orifice may be dependent upon the size of the canister utilizedwith the manifold system and/or the desired chemical flow rates. Duringuse, the manifold of this invention may be operated as follows. To pushchemical out of the canister 104 to the delivery point, the valves inthe manifold are appropriately opened and closed to allow pressurizedgas into the system and into the canister. In FIG. 4B, dashed line 220illustrates the path of pressurized gas entering canister 104, withdashed line 221 showing the path of liquid chemical exiting canister 104through a dip tube 91. Thus, pressurized gas from a source (not shown)is released by regulator 32 into line 31. The gas thereafter passesthrough open CGI 30, then through line 33, FLI 45, CBV 40, line 42,opened CP2 70, line 71, CI 90, and into canister 104. Pressure fromentering gas forces liquid chemical up the dip tube, and through CO 92,line 52, PLI 50, and out line 110 to the receiving point for example, aCVD process tool).

During use, the manifold of FIGS. 4J-4R may be operated as follows. Topush chemical out of the canister 104 to the delivery point, the valvesin the manifold are appropriately opened and closed to allow pressurizedgas into the system and into the canister. In, FIG. 4K, dashed line 320illustrates the path of pressurized gas entering 30 canister 104, withdashed line 321 showing the path of liquid chemical exiting canister 104through a dip tube 91. Thus, pressurized gas from a source (not shown)is released by regulator 32 into line 31. The gas thereafter passesthrough open CGI 30, then through line 33, FLI 45, CBV 40, line 42,orifice 43, T fitting 44, line 71, CI 90, and into canister 104.Pressure from entering gas forces liquid chemical up the dip tube, andthrough CO 92, line 52, PLI 50, and out line 110 to the receiving point(for example, a CVD process tool).

When a supply canister (even a full canister) is being changed out, thelines may be purged to rid the manifold of residual chemicals. The firststep to rid the manifold of residual chemicals is a cycle purge stepwhich includes a vacuum step and a flowing purge step respectively. Thecycle purge may include repeatedly performing the vacuum and flowingpurge in an alternating manner. A single vacuum step is discussed belowwith reference to FIG. 4L and a single flowing purge step is discussedbelow with reference to FIG. 4M. The vacuum step may be accomplished ina variety of ways, including via the configuration depicted by dashedline 350 FIG. 4L. Thus, in one embodiment, LPV 60 is opened such thatwhen VGS 10 is opened to allow gas into vacuum source 14 via lines 11and 12, a vacuum is drawn out to exhaust via line 13, with a vacuum thusbeing pulled on lines 15, 16, 63, 62, 42, 34, 33, 71, and 73.

In FIG. 4M, a flowing purge of the vacuum line dry down cycle purge isillustrated. In FIG. 4M, regulator 32 allows pressurized gas to enterline 31. With CGI 30 and LPV 60 open, the gas flows through lines 31,33, 34, 42, 71, 73, 62, 63, 16, 15, and 13 to thereby purge themanifold, as depicted in FIG. 4M by dashed line 360.

Next a depressurization step is performed to remove the head pressure incanister 104. For example, a procedure by which depressurization mayoccur is depicted in FIG. 4N. In one depressurization method, depictedby dashed line 330, VGS, 10 is opened to allow gas to flow from line 11through line 12 and into vacuum source 14 such that a vacuum isgenerated with the flow exiting via line 13 to exhaust. The vacuum whichis generated in source 14 pulls a vacuum on line 15, line 16, throughopen LPV 60, line 63, through LWO 61, line 62, T fitting 44, orifice 43,line 42, line 34, line 33, line 71, and open CI 90, thereby pulling avacuum on the head space of canister 104.

After depressurization, a liquid drain is instituted to clear the lines(weldments) of liquid. Thus, in FIG. 4O gas is introduced via regulator32 into line 31. CGI 30, CBV 40, and CO 92 are open such that gas flowsthrough lines 31, 33, 34, 41, 52, line 42, orifice 43, T fitting 44,line 71 and line 73 such that liquid chemical is forced back intocanister 104. The flow of gas during the line drain is illustrated bydashed line 340.

After the liquid drain, a flush liquid purge is instituted. As shown inFIG. 4P, a flush liquid may be introduced though flush liquid input 116.By opening FLI 45, CBV 40, and part of CO 92, flush liquid purges allwetted surface areas on the outlet of the manifold. Thus, flush liquidflows through lines 34, 41, 52, 73, 71, 42, and 62 as shown by dashedline 370. Further, LWO 61 is opened so that the flush liquid may exitthe manifold 102 through the waste outlet 118.

After the liquid purge, a canister removal cycle purge is institutedwhich includes a vacuum step and a flowing purge step respectively. Thiscycle purge removes any residual solvent vapors remaining after theflush liquid purge step. The vacuum step is depicted by dashed line 380FIG. 4Q. Thus, in one embodiment, LPV 60, part of CO 92, and CBV 40 areopened such that when VGS 10 is opened to allow gas into vacuum source14 via lines 11 and 12, a vacuum is drawn out to exhaust via line 13,with a vacuum thus being pulled on lines 15, 16, 63, 62, 71, 73, 52, 41,42, 34, and 33.

In FIG. 4R, a flowing purge is instituted as part of the canisterremoval cycle purge. In FIG. 4R, regulator 32 allows pressurized gas toenter line 31. With CGI 30, CBV 40, part of CO 92, and LPV 60 open, thegas flows through lines 31, 33, 34, 41, 42, 52, 73, 71, 62, 63, 16, 15,and 13 to thereby purge the manifold, as depicted in FIG. 4R by dashedline 390.

FIGS. 5-7 illustrate a variety of additional configurations for forminga chemical delivery system utilizing multiple purging techniques. Thetechniques of FIGS. 5-7 may be used with manifold valve configurationssuch as FIG. 4A or FIG. 4J. FIGS. 5A-5M illustrate a dual tanknon-refillable delivery system utilizing a medium level vacuum, flowingpurge, and liquid flush purge. Such a configuration may be utilized fora wide variety of the chemicals discussed herein. For example, in oneembodiment the configuration of FIGS. 5A-5M may be utilized for a liquidBST delivery system.

An exemplary purging sequence for the system of FIG. 5A is shown inFIGS. 5B-5M. As with FIGS. 4B-4I, dashed lines are used in FIGS. 5-7 toindicate the vacuum, gas, or liquid flows. Similarly, common valvesbetween the FIGS. 5-7 such as the FLI, VGS, LPV, CGI, CBV, PLI, CP2, CO,CI and LWO valves (where applicable) are labeled with the samenomenclature as in FIGS. 4A-4I. Further, where, additional canisters areused in a dual canister system numerals 1 and 2 are added to the end ofthe valve reference nomenclature to indicate the portion of the manifoldcoupled to the first canister and the second canister respectively.Thus, for example, two CO valves, CO1 and CO2 are provided as shown inFIG. 5A coupled to the first and second chemical canisters respectivelyand so forth for the other valves. As shown in FIG. 5A, the chemicaldelivery system 500 may include a first chemical source canister 502 anda second chemical source canister 504. A liquid flush source 506 (forexample a canister containing a solvent) and a liquid flush wastecontainer 508 (for example a canister) are also provided. Associatedwith the first source canister 502 are valves FLI1, CGI1, CBV1, CP2-1,CI1, CO1, LWO1, LPV1, and PLI1 which are coupled similarly to that asdescribed with reference to FIG. 4A. Additional valves SPV1 and SVS1 arealso associated with the source canister 502 as shown in FIG. 5A. Asimilar set of valves FLI2, CGI2, CBV2, CP2-2, CI2, CO2, LWO2, LPV2,PLI2, SPV2 and SVS2 are associated with the second source canister 504.The valves associated with each canister 502 and 504 may be contained ina single manifold or may be contained in two or more separate manifoldsof the chemical delivery system 500.

As also shown within FIG. 5A, the liquid flush source 506 may be coupledto valves SC1-SC6 and the liquid flush waste canister 508 may be coupledto valves SW1-SW8. The chemical delivery system may further includeregulators 512, flow restrictors 510, pressure transducers 514, andover-pressure check valves 516 as shown.

The operation of the chemical delivery system may be seen with referenceto FIGS. 5B-5M. FIG. 5B illustrates the chemical delivery run mode ofthe chemical delivery system 500. As shown in FIG. 5B, dashed lines 522indicate the flow of gas (for example He gas) from a gas source 518 toeach canister 502 and 504. The gas is used to force chemical from thecanisters 502 and 504 to OUTLET 1 and OUTLET 2 respectively as indicatedby dashed lines 524.

The purging of the sequences of FIGS. 5C-5M may be performed after therun mode of FIG. 5B is halted. As shown in the figures, the purgingsequence will be illustrated with reference to the lines and valvesassociated with the first chemical source canister 502, however, it,will be recognized that a similar sequence may be utilized with respectto the second chemical source canister. After the run mode, a cyclepurge step comprised of a Venturi vacuum dry down step and a flowingpurge step may be performed. The Venturi vacuum dry down step is shownby dashed line 530 of FIG. 5C and the flowing purge step is shown bydashed line 535 of FIG. SD. The cycle purge may be repeatedly performed.Then a canister depressurization may be performed as shown by dashedline 540 in FIG. 5E by use of the Venturi vacuum. A line drain of theoutlet line may then be performed as shown by dashed line 545 of FIG.5F. During the line drain, portions of the system may be maintainedunder vacuum as shown by dashed line 547. Next, another canisterdepressurization step may be performed as shown by dashed line 550 ofFIG. 5G.

A solvent flush may be accomplished by allowing gas from the gas inlet518 (as indicated by dashed line 553 to force solvent from the liquidflush canister 506 to the liquid waste container 508 as shown by dashedline 555 in FIG. 5H. In this manner, residual source chemical within thevalves and lines of the chemical delivery system may be flushed by asolvent liquid. During this step, portions of the system may bemaintained under vacuum as shown by dashed line 547. After the solventflush, a liquid drain step may be performed to drain to the liquid wastecontainer any of the solvent liquid remaining in the lines as indicatedby dashed line 560 of FIG. 5I. Again, during this step portions of thesystem may be maintained under vacuum as shown by dashed line 547. Theliquid waste container 508 may then be depressurized as shown by dashedline 565 in FIGURE J. The liquid flush steps of FIGURES H, I and J maythen be repeatedly performed in order to obtain a satisfactory purge ofthe source chemical from the systems valves and lines.

After the liquid flush steps, the system may be prepared for a canisterchange (the first source canister 502 in the example discussed herein)by cycle purge comprised of a vacuum step and a flowing purge step asshown in FIGURES K and L. As shown in FIGURE K, the dashed line 570indicates the vacuum step and as shown in FIGURE L the dashed line 575indicates the flowing purge step. The two step cycle purge process maybe performed repeatedly. While a canister is disconnected during thecanister exchange, a positive pressure and gas flow may be kept on thelines which connect to the canister inlet and outlet as shown in FIGUREM by dashed line 580. After reconnection of another canister, additionalcycle purges comprised of the vacuum step of FIGURE K followed by theflowing step of FIGURE L may then be performed repeatedly.

The embodiment discussed above with reference to FIGS. 5A-5M isillustrated as a non-refillable system (i.e. no refill between the firstchemical source canister 502 and the second chemical source canister504. However, a refillable system may be designed similar to thechemical delivery system 500 by the addition of a refill line betweenthe OUTLET 1 and an inlet to the second canister 504. In this manner thetechniques disclosed herein may be utilized with a refillable dualcanister system.

Yet another embodiment of the present invention is shown in FIGS. 6A-6N.The embodiment of FIGS. 6A-6N is a dual tank non-refillable chemicaldelivery system 600. The chemical delivery system 600 may be utilizedsuch that one chemical may be supplied from either of the chemicalsource canisters 602 or 604 with the system switching from one canisterto the next when the chemical level in one canister is low. Theembodiment of FIGS. 6A-6N may be used for delivery liquid chemicals,such is for example, TDEAT or TaEth. As shown in FIGS. 6A-6N, thisembodiment includes the use of multiple purge techniques. Thistechniques include a medium level vacuum (for example a Venturi vacuumsource), a flowing purge, flush liquid purge, and/or a hard vacuum. Aliquid flush source 606 such as a solvent containing canister isprovided as shown. The liquid flush waste may be disposed of within anempty chemical source canister 602 or 604 (i.e. the canister beingchanged out). Alternatively, a dedicated liquid flush waste canistersuch as shown in FIG. 5A may be utilized. In yet another alternative,the liquid waste may be flushed to a hard vacuum. As will be discussedin greater detail below, a flush liquid purge may also be optionallyutilized for aiding the draining of process lines to a process linedrain reservoir 608.

Associated with the first source canister 602 are valves FLI1, CGI1,CBV1, CP2-1,1 CI1, CO1, LPV1, LWO1, SVS1, and PLI1 which are coupledsimilar to that as described with reference to FIG. 5A. A similar set ofvalves FLI2, CGI2, CBV2, CP2-2, CI2, CO2, LPV2, PLI2, LWO2 and SVS2 areassociated with the second source canister 604. The valves associatedwith each canister 602 and 604 may be contained in a single manifold ormay be contained in two or more separate manifolds of the chemicaldelivery system 600.

As also shown within FIG. 6A, the liquid flush source 506 may be coupledto valves SC1-SC5. The chemical delivery system may further includeregulators 612, pressure transducers 614, inert gas source 618 (forexample helium) and over-pressure check valves 616 as shown. A degasmodule 624 may be utilized to remove gas (such as helium) from theliquid being supplied to the process tool. Various portions of thechemical delivery system 600 may be connected to a hard vacuum as shownby hard vacuum connections 620. OUTLETS which supply liquid chemical toa process tool are also provided. A flush line 622 between valve SC1 andvalve 626 is not shown in its entirety so as to simplify theillustration, however, the flush line 622 is one continuously connectedline.

The operation of the chemical delivery system may be seen with referenceto FIGS. 6B-6N which illustrate the supply of chemical from the firstchemical source canister 602 while the second chemical source canister604 is idle and the steps performed when the first chemical sourcecanister 602 is replaced. FIG. 6B illustrates the chemical delivery runmode of the chemical delivery system 600. As shown in FIG. 6B, dashedline 628 indicates the flow of gas (for example He gas) from a gassource 618 to a canister 602. The gas is used to force chemical from thecanister 602 to the outlets OUTLET-1 and OUTLET-2 as indicated by dashedline 629. The use of two or more outlets allows chemical to be suppliedfrom a single chemical canister to two or more process tools. Thus, thechemical outlet is configured in a multi-branch outlet configuration.Further, chemical supply to OUTLET-1 and OUTLET-2 may be independentlycontrolled through valves CC-1 and CC-2 respectively. Thus, chemical maysupplied from both outlets at the same time or from only OUTLET-1 orfrom only OUTLET-2. Valves 0-1 and 0-2 may be manual valves which areleft open during normal operations.

The purging of the sequences of FIGS. 6C-6N may be performed after therun mode of FIG. 6B is halted. While the lines and valves associatedwith one canister are being purged, the other canister may be operatingin the run mode. As shown in the figures, the purging sequence will beillustrated with reference to the lines and valves associated with thefirst chemical source canister 602, however, it will be recognized thata similar sequence may be utilized with respect to the second chemicalsource canister. After the run mode of the first chemical sourcecanister 602 is halted, a cycle purge step comprised of a Venturi vacuumdry down step and a flowing purge step may be performed. The Venturivacuum dry down step is shown by dashed line 630 of FIG. 6C and theflowing purge step is shown be dashed line 635 of FIG. 6D. The cyclepurge may be repeatedly performed. Then a canister depressurization maybe performed as shown by dashed line 640 in FIG. 6E by use of theVenturi vacuum. A line drain of the outlet line may then be performed asshown by dashed line 645 of FIG. 6F. During the line drain, portions ofthe system may be maintained under vacuum as shown by dashed line 647.Next, another canister depressurization step may be performed as shownby dashed line 650 of FIG. 6G.

A solvent flush may be accomplished by allowing gas from the gas inlet618 (as indicated by dashed line 653 to force solvent from the liquidflush canister 606 to the chemical source container 602 as shown bydashed line 655 in FIG. 6H. In this manner, residual source chemicalwithin the valves and lines of the chemical delivery system may beflushed by a solvent liquid. During this step, portions of the systemmay be maintained under vacuum as shown by dashed line 647. After thesolvent flush, a liquid drain step may be performed to drain to theliquid waste container any of the solvent liquid remaining in the linesas indicated by dashed line 660 of FIG. 6I. Again, during this stepportions of the system may be maintained under vacuum as shown by dashedline 647. The steps of FIGS. 6G, 6H, and 6I may then be repeatedlyperformed in order to obtain a satisfactory purge of the source chemicalfrom the systems valves and lines.

Alternatively, rather than the steps of FIGS. 6H and 6I, the liquidwaste may be flushed to a hard vacuum source. Thus, the step of FIG. 6Jmay be used in place of the step of FIG. 6H. As shown by dashed line 656in FIG. 6J, the solvent from the liquid flush canister 606 may beflushed to a hard vacuum connection 620 (rather than the chemical sourcecanister as shown in FIG. 6H). Then after the solvent flush of FIG. 6J,a liquid drain step may be performed to drain to the liquid wastecontainer any of the solvent liquid remaining in the lines as indicatedby dashed line 661 of FIG. 6K. Again, during this step portions of thesystem may be maintained under vacuum as shown by dashed line 647. Thesteps of FIGS. 6G, 6K, and 6J may then be repeatedly performed in orderto obtain a satisfactory purge of the source chemical from the systemsvalves and lines.

After the liquid flush steps, the system may be prepared for a canisterchange (the first source canister 602 in the example discussed herein)by a cycle purge comprised of a vacuum step and a flowing purge step asshown in FIGS. 6L and 6M. As shown in FIG. 6L, the dashed line 570indicates the vacuum step and as shown in FIG. 6M the dashed line 575indicates the flowing purge step. The two step cycle purge process maybe performed repeatedly. While a canister is disconnected during thecanister exchange, a positive pressure and gas flow may be kept on thelines which connect to the canister inlet and outlet as shown in FIG. 6Nby dashed line 580. After reconnection of another canister, additionalcycle purges comprised of the vacuum step of FIG. 6L followed by theflowing step of FIG. 6M may then be performed repeatedly.

The flush line 622 may be utilized to provide a liquid flush for use influshing the process lines connected between the outlets (OUTLET-1 andOUTLET-2) and the process tool. Thus, liquid solvent may be providedfrom the liquid flush canister 606 to the flush line 622 through thevalve 626 so that the process lines may be flushed with the liquidsolvent similar to the techniques described above the for flushing theother lines exposed to the chemical supplied from the source chemicalcanisters. The waste from the process line drain may be provided to theprocess line drain reservoir 608. The reservoir 608 may or may not beenclosed within the cabinet housing the chemical delivery system. Inanother embodiment, a reservoir 608 may not be utilized, but rather theliquid waste may be provided to a hard vacuum connection similar to thetechnique discussed with reference to FIGS. 6J and 6K. Thus, the liquidwaste may be disposed off through the hard vacuum connection 620 that islocated proximate the valve 626. In either cases, multiple purgetechniques including vacuum, flowing inert gas, and liquid flushtechniques may be utilized to purge the process lines and associatedvalves.

A process for draining and flushing the process line may be seen in moredetail with reference to FIG. 6A. The draining and flushing process isdescribed herein with reference to OUTLET-1 (thus valve O-1 will be openthrough this example), but it will be recognized that a similar processmay be utilized to drain the process lines between OUTLET-2 and theprocess tool. Moreover, the draining and flush process described hereinwith reference to OUTLET-1 may be performed while chemical is beingsupplied through OUTLET-2 or vice-versa. Thus, one branch of the outletsmay be purged while the other branch is still operating to providechemical to the process tool.

To initialize the process line drain and flush, the process line drainreservoir 608 may be depressurized by use of the hard vacuum connection620 and opening valves PV-ISO and Cl-DR. Then pressure in the processline drain reservoir outlet line may be relieved by opening the CO-DRand MDV valves. Next valve MP-1 may be opened so that the line to theprocess tool is now under vacuum and liquid will drain to the reservoir.After the process line has been placed under vacuum, the next step is toflow an inert gas (supplied by the process tool) from the process toolthrough the valves OUTLET-1, CC-1, MP-1, MDV to the process line drainreservoir through valve CO-DR. This flowing purge step pushes any fluidin the process lines into the reservoir 608. Multiple cycles of thevacuum and inert gas push steps may be performed.

Next, valve MP-1 may be closed and another canister depressurizationperformed by opening valves PV-ISO and CI-DR. After depressurization,the valves PV-ISO and CI-DR may be closed. Then any liquid in the linebetween the valves MP-2 and MP-1 may be pushed to the drain reservoir byusing the inert gas source 618 by opening valves P-ISO, PCR, MDV andCO-DR.

Next a hard vacuum followed by a liquid flush may be repeatedlyperformed. First, the process lines may be put under the hard vacuum byopening valves PV-ISO, FP3-DR, MDV, and MP-1. After the hard vacuum isceased, the process lines may be subjected to a liquid flush by openingvalves PSV, PCR, and MP-1. This allows flush liquid to be pushed up tothe process tool. Then the PSV valve may be closed and the MDV and CO-DRvalves opened to allow the 1 liquid in the process lines to drain downinto the drain reservoir 608. These hard vacuum and liquid flush stepsmay then be repeated (for example 3-5 cycles).

Thus, the valves and lines associated with the multi-branch outlets andthe reservoir (valves O-1, O-2, CC-1, CC-2, MP-1, MP-2, PCR, MDV, HE-DR,P-ISO, PSV, PV-ISO and associated lines, which collectively may bereferred to as a distribution or outlet manifold) may be purged byutilizing multiple purge techniques. Thus, it may be seen that the useof multiple purge techniques described with reference to purging valvesassociated with a chemical supply canister is also beneficial for usewith purging other valves of the chemical delivery system. When utilizedwith valves associated with a supply canister, the multiple purgetechniques may provide benefits for limiting contamination which mayoccur during canister change-outs, canister refills, etc. When utilizedwith the valves associated with the multi-branch outlets (thedistribution manifold), the multiple purge techniques provide benefitsfor limiting contamination which may occur when a process line is takenoff-line and/or during start-up of use of a process line. Moreover, themultiple purge techniques may be utilized on one branch of the outlets(for example OUTLET-1) while the other branch is still supplyingchemical (for example OUTLET-2) or vice versa. Thus, the use of multiplepurge techniques to limit contamination is useful for the canistermanifold (the valves associated with a given canister) and thedistribution manifold. Though discussed herein as separate manifolds, itwill be recognized that the canister manifold and distribution manifoldmay be considered as sub-parts of one larger manifold which includessome or all the valves of FIG. 6A.

Yet another embodiment of the present invention is shown in FIGS. 7A-7M.The embodiment of FIGS. 7A-7M is a dual tank refill chemical deliverysystem 700. The embodiment of FIGS. 7A-7M may be used for deliveryliquid chemicals, such as for example, TDEAT. As shown in FIGS. 7A-7M,this embodiment includes the use of multiple purge techniques. Thistechniques include a medium level vacuum, a flowing purge, and a hardvacuum. As will be discussed in greater detail below, a liquid flush mayalso be optionally utilized with this embodiment for aiding the drainingof process lines. The optional liquid flush may be advantageous in thatthe long length of the process lines and their size may prevent anadequate purge of those process lines for very low vapor pressurechemicals such as TDEAT when only a medium level vacuum, a flowingpurge, and a hard vacuum are used. If the purge of the process lines isinadequate, the flush liquid purge will complete the purge process.

The chemical delivery system 700 of FIG. 7A may be utilized such thatone chemical may be supplied from the process canister 704 (for examplea 4 liter canister) to the process tool. The process canister 704 may berefilled from a bulk canister 702 (for example a 5 gallon canister). Thesystem is designed to allow the bulk canister 702 to be removed andreplaced when the chemical level of the bulk canister is low. The systemalso includes a process line drain reservoir 708, a liquid flush inlet705 (which may be connected to a user's facility solvent lines or asolvent containing canister similar to as described above), and a hardvacuum connection 720 which is coupled to a hard vacuum source (forexample the hard vacuum of a process tool). Associated with the bulkcanister 702 are valves CGI-L, CBV-L, CP2-L, CI-L, CO-L, LPV-L, andPLI-L and associated with the process canister 704 are valves CGI-R,CBV-R, CP2-R, CI-R, CO-R, LPV-R, and PLIR (as used in FIGS. 7A-7M “-L”indicates valves associated with the bulk canister and “-R” indicatesvalves associated with the process canister). A valve HVI is coupled tothe hard vacuum 720 as shown and a valve VGI is coupled to the VGSvalve. The various valves may be contained in a single manifold or maybe contained in two or more separate manifolds of the chemical deliverysystem 700. The chemical delivery system may further include regulators712, pressure transducers 714, inert gas source 718 (for example helium)and over-pressure check valves 716 as shown. A degas module 724 may beutilized to remove gas (such as helium) from the liquid being suppliedto the process tool. Various portions of the chemical delivery system600 may be connected to a hard vacuum as shown by hard vacuumconnections 720. OUTLET1 and OUTLET2 supply liquid chemical to a processtool in a multi-branch outlet configuration similar to as discussedabove with reference to FIG. 6B.

A refill step is illustrated in FIG. 7B. As shown in FIG. 7B, gas flowindicated by dashed line 730 forces chemical from the bulk canister 702to the process canister 704 as indicated by dashed line 732. FIG. 7Cillustrates the chemical delivery run mode of the chemical deliverysystem 700. As shown in FIG. 7C, dashed line 728 indicates the flow ofgas (for example He gas) from a gas source 718 to a canister 704. Thegas is used to force chemical from the canister 704 to the OUTLET1 andOUTLET2 as indicated by dashed line 729.

The purging of the sequences of FIGS. 7D-7M may be performed when it isdesired to change the bulk canister 702. The purging techniques of FIGS.7D-7M may be performed while the system is delivering chemical fromprocess canister 704 to the process tool as shown in FIG. 7C by dashedlines 728 and 729, Thus, though not shown in FIGS. 7D-7M the gas andchemical flows indicated in FIG. 7C by clashed lines 728 and 729 may bepresent within each step of those figures. When a purge is desired, acycle purge step comprised of a Venturi vacuum dry down step and aflowing purge step may be performed. The Venturi vacuum dry down step isshown by dashed line 730 of FIG. 7D and the flowing purge step is shownbe dashed line 735 of FIG. 7E. The cycle purge may be repeatedlyperformed. Then a canister depressurization may be performed as shown bydashed line 740 in FIG. 7F by use of the Venturi vacuum. A line drain ofthe outlet line may then be performed as shown by dashed line 745 ofFIG. 7G. During the line drain, portions of the system may be maintainedunder vacuum as shown by dashed line 747. Next, another canisterdepressurization step may be performed as shown by dashed line 750 ofFIG. 7H.

The system may then be prepared for a hard vacuum purge by firstperforming a Venturi vacuum as indicated by dashed lines 755 of FIG. 7I.The hard vacuum purge may then be performed as indicated by dashed lines760 of FIG. 7J. After the system is subjected to a hard vacuum, apositive pressure and gas flow may be kept on the lines which 34 connectto the canister inlet and outlet as shown in FIG. 7K by dashed line 780and the canister 702 may be disconnected from the system. Afterreconnection of another canister 702, a Venturi vacuum step as indicatedby dashed line 782 of FIG. 7L may be performed followed by apressurization step as indicated by dashed line 784 of FIG. 7M. Thevacuum and pressurization steps of FIGS. 7L and 7M may then be performedrepeatedly with the cycle ending with a Venturi vacuum step as shown inFIG. 7L. Finally, a hard vacuum step as shown by dashed line 760 of FIG.7J may be performed. At this point the system is ready to utilize thenew bulk canister 702.

Similar to as described above with respect to the system 600, a flushinlet 705 is provided to system 700 of FIG. 7A to allow for a liquidpurge of the process lines. The waste from the liquid purge of theprocess lines may be collected in a process line drain reservoirutilizing the techniques as disclosed herein. The process line drainreservoir 708 may or may not be located within the same cabinet as therest of the system 700. Moreover as with system 600, the draining andflush process of OUTLET-1 may be performed while chemical is beingsupplied through OUTLET-2 or vice-versa. Thus, one branch of the outletsmay be purged while the other branch is still operating to providechemical to the process tool. Moreover as also discussed above withreference to FIG. 6A, the purging of the outlets takes advantage of thebenefits of a multiple technique purge of the present invention(including for example, a vacuum purge, a flowing gas purge and a liquidflush purge).

The cabinet for housing a chemical delivery system of the presentinvention may be constructed in a wide variety of manners. Exemplarycabinet designs are shown in U.S. Pat. No. 5,711,354 and pendingapplication Ser. No. 09/141,865 filed Aug. 28, 1998, the disclosures ofwhich are expressly incorporated herein by reference. FIG. 8 shows ageneral chemical delivery system cabinet 1000. As shown in FIG. 8, thecabinet includes a plurality of cabinet walls. The walls may includesides, a top and a bottom which define an interior cabinet space. In oneembodiment, the cabinet may be constructed to render it suitable for usein hazardous, explosive environments. In general, this is accomplishedby isolating all electronic components in areas that are blanketed withan inert gas. In this way, a spark emanating from an electroniccomponent will be in an environment having essentially no oxygen, whichsignificantly reduces the likelihood of an explosion due to vapors thatmay be present in the cabinet.

Because some of the chemicals described above may crystallize at or nearroom temperature it may be desirable to provide temperature control ofthe environment within the cabinet 1000. Thus, for example, a desiredcabinet temperature for TaEth may be maintained at an internaltemperature of approximately 30 degrees Celsius. Additionally, byheating the cabinet the evaporation of chemicals from the manifold linesmay be accelerated thus improving the purge of chemicals in themanifold.

In one embodiment, the cabinet may be heated by attaching a heatingelement to at least one door of the cabinet. A door suitable for usewith a heating element is shown in FIGS. 9A and 9B. As shown in FIG. 9A,the door 1003 may include an air vent 1004 and a heater interface 1006.Generally a positive flow of air into the cabinet is maintained(independent of use of a heater) through a vent such as air vent 1004for safety considerations by venting an exhaust line out of the cabinet.

As can be seen in more detail in FIG. 9B, the heater interface 1006 maybe a recessed cavity having a back wall 1008 recessed into the door1003. Within the heater interface 1006 a flat heater element (forexample an 8×18 inches flat electric silicon heater) may be adhered tothe heater interface back wall 1008. The heater interface 1006 may beformed as an aluminum insert placed into a cavity of the door. The useof aluminum or any other material that allows for heat transfer willresult in heat transferring from the heater interface to the inside ofthe cabinet. Placement of the heater element in this manner convenientlyallows access to the heater from the front of a cabinet and helpsisolate the heater from any explosive gases within the cabinet. Thoughnot shown, a cover may be placed over the heater interface 1006 toprotect the heater element and the end user.

The transfer of heat from the heater element to the cabinet is alsoaided through the use of air vent 1004, fins 1010 and an airflowstructure 1012 that serves to funnel a flow of air over the fins 1010.Thus, the structure 1012 and heater serve to form a confined passage forthe flow of air. Aluminum fins 1010 attached to the heater interfaceback wall 1008 act to increase the metal surface area for improved heattransfer. Air flow structure 1012 provides a path to force air whichflows in air vent 1004 (as indicated by air flow arrow 1014) to flowpast the back wall 1008 and fins 1010. Warm air may then enter thecabinet as indicated by air flow arrow 1014. In this manner the cabinetmay be heated in an efficient and cost effective manner through the useof a heater element coupled to the front door of the cabinet. Though theheater interface of FIGS. 9A and 9B is shown as a cavity recessed intothe door 1003, the heater interface may be configured in other manners.For example, the back wall of the heater interface may be placed on anoutside panel of the door and thus the heater interface and element mayprotrude outside of the door. Similarly, the back wall of the heaterinterface may be placed in an opening of the door such that the backwall is flush with the door. Moreover, the heater element may be coupledto other cabinet walls such as the sides, back, top or bottom in similarmanners. Thus, heat may be transferred through the walls and into thecabinet from an element external to the cabinet walls.

Further modifications and alternative embodiments of this invention willbe apparent to those skilled in the art in view of this description.Accordingly, this description is to be construed as illustrative onlyand is for the purpose of teaching those skilled in the art the mannerof carrying out the invention. It is to be understood that the forms ofthe invention herein shown and described are to be taken as presentlypreferred embodiments. Equivalent elements may be substituted for thoseillustrated and described herein, and certain features of the inventionmay be utilized independently of the use of other features, all as wouldbe apparent to one skilled in the art after having the benefit of thisdescription of the invention.

What is claimed is:
 1. A method of forming a layer upon a semiconductorsubstrate, comprising: providing the semiconductor substrate, thesubstrate having one or more layers; providing a deposition processtool; coupling a chemical delivery system to the deposition process toolto provide a low vapor pressure liquid chemical to the depositionprocess tool; periodically purging at least a portion of the chemicaldelivery system of the low vapor pressure liquid chemical, the purgingincluding the use of at least three different purging techniques eachhaving a separate source that is separate from a source containing thelow vapor pressure liquid chemical; and depositing the layer upon thesemiconductor substrate by utilizing the low vapor pressure liquidchemical within the deposition process tool.
 2. The method of claim 1,wherein the layer is a dielectric layer.
 3. The method of claim 2,wherein the low vapor pressure liquid chemical is TaEth or BST.
 4. Themethod of claim 3, the chemical delivery system having at least a firstcanister and a second canister, the low vapor pressure liquid chemicalbeing provided to the semiconductor process tool from the secondcanister, the chemical delivery system being capable of refilling thesecond canister from the first canister.
 5. The method of claim 3, thechemical delivery system having at least a first canister and a secondcanister, the chemical delivery system being capable of providing thelow vapor pressure chemical from both the first canister and the secondcanister to the semiconductor process tool.
 6. The method of claim 3,the at least three different purging techniques comprising at least afirst vacuum step and a flowing purge step utilizing an inert gas. 7.The method of claim 6, the at least three different purging techniquesfurther comprising a liquid flush step.
 8. The method of claim 1, thelayer containing titanium.
 9. The method of claim 8, wherein the lowvapor pressure liquid chemical is TDEAT.
 10. The method of claim 9,wherein the layer comprises titanium nitride.
 11. The method of claim 9,the chemical delivery system having at least a first canister and asecond canister, the TDEAT being provided to the semiconductor processtool from the second canister, the chemical delivery system beingcapable of refilling, the second canister from the first canister. 12.The method of claim 9, the chemical delivery system having at least afirst canister and a second canister, the chemical delivery system beingcapable of providing TaEth from both the first canister and the secondcanister to the semiconductor process tool.
 13. The method of claim 9,the at least three different purging techniques comprising at least afirst vacuum step and a flowing purge step utilizing an inert gas. 14.The method of claim 13, the at least three different purging techniquesfurther comprising a liquid flush step.